6.2.1. Cloning and Biotechnology

Natural clones of plants

Vegetative propagation. Part of a plant is separated, then develops into a new plant genetically identical to the original. English Elm does not produce viable seed, so naturally self-propagates using its roots.

Plant cutting for cloning

Stem is cut between the leaf and nodes. Replanted and allowed to grow, sometimes with the use of plant hormones.

Artificial clones of plants

Tissue culture; sample placed on various nutrient-containing mediums to encourage cell division and shoot growth. Micropropagation; material produced from tissue culture is rapidly multiplied to produce large numbers of plants.

Advantages of artificial plant cloning in agriculture

• Large number of plants can be produced regardless of weather conditions.

Disadvantages of artificial plant cloning in agriculture

• Reduces genetic variation, making them susceptible to disease.

Natural cloning in animals

Monozygotic twins; embryo splits during development to produce two genetically identical individuals.

Artificial clones of animals

Somatic cell nuclear transfer; differentiated cell from parent fused with an enucleated egg cell. The cell develops into an embryo and can be implanted into a womb. Embryo splitting; same process by which twins form, performed artificially.

Arguments surrounding cloning in animals

• Quick process suited to the growing population of Earth. + Can preserve endangered species. - Cloned animals often suffer from health problems. - Low genetic diversity.

Microorganisms in biotechnological processes

Rapid growth in a variety of environmental conditions. Can be genetically engineered. Reduces use of chemicals, beneficial to the environment.

Uses of microorganisms in biotechnology

Food; baking, brewing, yogurt, cheese. Medicine; penicillin, insulin. Environmental; removing pollution (bioremediation).

Advantages of using microorganisms for food production

• Production rate easily varied. + Not dependent on climate. + Long-lasting. + Uses waste products.

Disadvantages of using microorganisms for food production

• Lack of flavour. - Proteins must be isolated and purified. - Contains different amino acids to animal proteins.

Aseptic technique

Everything must be kept completely sterile so that no unwanted microorganisms are present in the culture.

Three steps of growing microorganisms

1. Sterilisation; part of the aseptic technique. 2. Inoculation; microorganism introduced to agar plate by streaking, seeding, or spreading. 3. Incubation; placed in warm environment for 24-48 hours to grow.

Batch fermentation

Closed environment, competition for resources, maintains culture in stationary phase, easy to set up, less efficient.

Continuous fermentation

Products continually removed, maintains culture in log phase, difficult to set up, more efficient.

Maximising yield growth conditions

●Temperature maintained at optimum. ●Sufficient nutrient supply. ●Aerobic conditions to prevent products of anaerobic respiration. ●pH kept constant to maximise enzyme activity.

Growth curve phases of a microorganism in a closed culture

●Lag= cells increase in size and take in water. Population constant. ●Log= cells divide. Population increases exponentially. ●Stationary= nutrient levels decrease, slowing growth rate. Population stabilizes. ●Death= toxic metabolites increase to a point that kills cells. Population declines.

Lag phase

1 - Lag

Log phase

2 - Log

Stationary phase

3 - Stationary

Death phase

4 - Death

Formula for bacterial growth

N = N0 x 2n ●N = number of bacteria currently in the population ●N0 = number of bacteria in the population at the beginning ●n = number of divisions

Immobilised enzyme

An enzyme attached to an inert material in order to restrict its movement and hold it in place during a reaction so that it can be reused.

Methods of immobilising enzymes

1. Bonding= enzyme binds with support ionically (adsorption) or covalently. 2. Entrapment= enzyme placed in a semi-permeable material that allows diffusion of the substrate and product. 3. Membrane separation= a partially permeable membrane separates enzyme from substrate.

Uses of immobilised enzymes

●Glucose to fructose conversion. ●Semi-synthetic penicillin production. ●Lactose to glucose/galactose conversion. ●Pure samples of amino acids. ●Dextrins to glucose conversion.

Evaluate the use of immobilised enzymes

• Product is not contaminated by enzyme, so does not need to be purified. + Enzymes can be reused. + Enzymes are protected from harsh environment. - Expensive. - Reaction rate is slower as enzymes cannot move.